Production of stretched artificial yarns and textile materials made therefrom



30, 1950 D. FINLAYSON ETAL 2,509,292 PRODUCTION OF STRETCHED ARTIFICIAL YARNS AND TEXTILE MATERIALS MADE THEREFROM Filed Oct. '7, 194'! hot water. ity can be obtained by saponifying such stretched Patented May 30, 1950 PRODUCTION OF s'rmrroiin'n ARTIFICIAL YARNS AND TEXTILE MATERIALS MADE THEREFROM Donald Finlayson and Frank Brentnall Hill, Spondon, near Derby, England, assignors to Celanese Corporation of America, a corporation of Delaware Application October 7, 1947, Serial No. 778,392

In Great Britain October 17, 1946 8 Claims. 1

This invention relates to the production of stretched artificial yarns and textile materials made therefrom. It will be described with particular reference to yarns having a basis of an and the filaments are set, the set filaments then being formed into yarns. Filaments and yarns so formed have many valuable properties. It is, however, well known that their tenacity can be considerably increased if they are subsequently stretched while in a softened condition, for example to 5, 10 or more times their original length, preferably in an atmosphere of wet steam or in Materials having a still higher tenacc'ellulose acetateyarns, which then consist of regenerated cellulose.

In the spinning and stretching of cellulose acetate materials as described above, the filaments leaving the spinning cell are conveniently formed into yarns and wound up on bobbins, and the bobbins transferred to the stretching machines. On the stretching machine the yarn is unwound from the bobbin and passed through two positively driven non-slip feed devices, e. g. two pairs of nip rollers, the second of which runs at a higher speed than the first so as to impart to the yarn the desired degree of stretch. Between the two feed devices the yarn passes through a stretching chamber containing a softening agent, preferably wet steam or water ata temperature substantially above 100C. and under the corre-.-. sponding pressure, in which the actual stretching takes place. After passing through the second feed device the yarn is rewound.

It has, however, been found that stretched cellulose acetate yarns so made often suifer from a pronounced lack of uniformity, which shows itself for example in variations in tenacity along the length of the yarn, and in the uneven dyeing of fabrics made from the stretched yarn. This lack of uniformity has been attributed to the presence of residualacetene in the yarn, and this theory found support in the fact that the lack of uniformity can be overcome by ageing the yarn, i. e. by allowing the bobbins to stand for a number of days, for example a fortnight or more, so that all the acetone in the yarn is removed by evaporaovercome to some extent without ageing the yarn by altering the activity of the softening agent, e. g. the pressure of wet steam, in accordance with the tension produced in the yarn by the stretching operation, but this is difficult and inconvenient to effect in a commercial process, and is impracticable when a large number of ends of yarn are stretched simultaneously in a single stretching chamber.

We have however now found that this lack of uniformity in the stretched yarn is not due to the presence of acetone per se, but to diiferences, which may be quite small, between the acetonecontent of different sections of the yarn. We have also found that the acetone-content of the yarn as it leaves the spinning cell is substantially uniform, but thatdifferential evaporation of acetone from different parts of the bobbin or other yarn package, and also as between individual packages, very soon causes sufiicient irregularity of acetone-content along the length of the yarn to give rise to the lack of uniformity in the stretched yarns. The present invention makes use of these facts.

In accordance with the present invention, in a process for the manufacture of artificial yarns in which the yarns are produced by a spinning method which leaves in the yarns a small proportion of a volatile solvent or swelling agent for the material of the yarns and are subsequently stretched while in a softened condition, the amount of the volatile solvent or swelling agent in the yarns is maintained substantially constant from the time they are Wound up at the spinning frame to the time they enter the stretching machine. Thus when cellulose acetate yarns are made by dry-spinning a solution of cellulose acetate in acetone and subsequently stretching the products, the bobbins or other yarn packages, from the time they are wound up at the spinning frame to the time they are unwound at the stretching machine, are kept under such conditions that the evaporation of acetone therefrom is substantially prevented. By this means we are able to dispense with the inconvenient and time-wasting ageing operation, and also to keep the activity of the softening agent constant'e. g. to keep the pressure of wet steam constant, and still produce a uniform yarn. Moreover the activity of the softening agent, e. g. the pressure of wet steam, may be lower than when the yarn is aged before being stretched.

In the preferred method of putting the invention into practice, the bobbins, as soon. as they tion before the yarnis stretched. It can also be 56 have been filled at the spinning frame. are transferred to containers which are then closed, and are kept in the containers until the yarn is to be stretched. If desired the bobbins may then be removed from the containers and fitted to the stretching machine, but we have found it much better to leave the bobbins in the containers during the whole of the stretching operation, the containers being provided with narrow orifices for the passage of the yarns as they are fed from the bobbins to the stretching machine. When working in this way, the amount of acetone lost from the yarns by evaporation between the time when the yarns leave the spinning cell and the time when they enter the stretching machine is negliible.

A form of container which is very suitable for the practice of the invention is illustrated in the accompanying drawing, which represents a sectional side elevation of the container.

The container consists in a rectangular box I fitted with pegs 2 on which bobbins may be placed. The box is provided with a removable lid 3, which can be held tightly in position by means of bolts and wing-nuts; so as to give a substantially airtight seal. The lid is provided with small orifices 5 of about the same diameter as the yarn with which the box is to be used, each orifice being situated in line with the axis of a particular peg when the lid is in position. If desired these orifices may be formed in small members which can be screwed into tapped holes in the lid. and which are interchangeable with members containing ori fices of diiferent diameter. On one peg a bobbin 6 is shown in position, with its yarn end 1 threaded through the appropriate orifice.

The method of using the box illustrated is as follows: Bobbins taken from the spinning frame are at once placed in the box, one on each peg,

and the yarn ends threaded through the appropriate orifices in the lid; the lid is then placed in position and the wing-nuts screwed down tightly. On arrival at the stretching machine the yarn ends are threaded into the machine and stretching carried out without removing the bobbins from the box.

Although the container illustrated holds five bobbins, containers holding any desired number of bobbins, from 1 upwards, can be employed. For instance a large container capable of holding a complete creel of bobbins can be used.

After being stretched the cellulose acetate yarns may be given any desired treatment; for example they may be shrunk to some extent to improve their extensibility. They may if desired be saponified either partially or completely. The stretched yarns, whether or not they are also saponlfied, may be used for the production of fabrics and other textile materials, for example by weaving, knitting or netting,

Although the invention has been described with particular reference to cellulose acetate yarns, it can be applied to other yarns which are made by a spinning method which leaves a small proportion of a volatile solvent or swelling agent in the yarns, and which are subsequently stretched, for example yarns having a basis of another organic derivative of cellulose, e. g. cellulose propionate or ethyl cellulose, or of a purely synthetic composition, for example polyacrylonitrile or a copolymer of vinyl chloride with vinyl acetate or acrylonitrile.

The invention is not restricted to the manufacture of yarns made up of a number of individual filaments, but is also useful in the manu facture of single continuous filaments of considerable denier and of structures made by causing a number of individual filaments to coalesce; the term yarns as used in the present specification and in the claims, is wherever the context allows, to be understood as including materials of these kinds.

Having described our invention, what we desire to secure by Letters Patent is:

1. A process for the manufacture of artificial yarns in which the yarns are produced by a spinning method which leaves in the yarns a small proportion of a volatile solvent or swelling agent for the materials of the yarns, are wound up at the spinning frame, and are subsequently stretched while in a softened condition, which comprises holding the wound yarn packages under conditions such that evaporation of the volatile solvent or swelling agent is substantially prevented from the time the yarns are wound up at the spinning frame to the time they enter the stretching machine. 7

2. A. process for the manufacture of artificial yarns having a basis of an organic derivative of cellulose in which the yarns are produced by a spinning method which leaves in the yarns a small proportion of a volatile solvent or swelling agent for the materials of the yarns, are wound up at the spinning frame, and are subsequently stretched while in a softened condition, which comprises holding the wound yarn packages under conditions such that evaporation of the volatile solvent or swelling agent is substantially pre vented from the time the yarns are wound up at the spinning frame to the time they enter the stretching machine.

3. A process for the manufacture of artificial yarns having a basis of cellulose acetate in which the yarns are produced by a spinning method which leaves in the yarns a small proportion of acetone, are Wound up at the spinning frame, and

are subsequently stretched while in a softened condition, which comprises holding the wound yarn packages under conditions such that evaporation of the acetone is substantially prevented from the time the yarns are wound up at the spinning frame to the time they enter the stretching machine.

4. A process for the manufacture of artificial yarns in which the yarns are produced by a spinning method which leaves in the yarns a small proportion of a volatile solvent or swelling agent for the material of the yarns, are wound up at the spinning frame, and are subsequently stretched while in a softened condition, which comprises at once transferring the wound yarn packages at the spinning frame to containers which are sufficiently airtight to prevent any but a negligible amount of evaporation of the solvent or swelling agent and keeping them in these containers until the yarn is to be stretched.

5. A process for the manufacture of artificial yarns having a basis of cellulose acetate in which the yarns are produced by a spinning method which leaves in the yarns a small proportion of acetone, are wound up at the spinning frame, and are subsequently stretched while in a softened condition, which comprises at once transferring the wound yarn packages at the spinning frame to containers which are sumciently airtight to prevent any but a negligible amount of evaporation of the acetone and keeping them in these containers until the yarn is to be stretched.

6. A process for the manufacture of artificial 7| yarns in which the yarns are produced by a spinning method which leaves in the yarn a small proportion of a volatile solvent or swelling agent for the materials of the yarns, are wound up at the spinning frame, and are subsequently stretched while in a softened condition, which comprises at once transferring the wound yarn packages at the spinning frame to containers which are sufiiciently airtight to prevent any but a negligible amount of evaporation of the solvent or swelling agent and are provided with orifices of diameter approximately equal to the diameter of the yarn, and feeding the yarn to the stretching machine through the said orifices while the packages remain in the containers.

1. A process for the manufacture of artificial yarns having a basis of an organic derivative of cellulose in which the yarns are produced by a spinning method which leaves in the yarn a small proportion of a volatile solvent or swelling agent for the materials of the yarns, are wound up at the spinning frame, and are subsequently stretched while in a softened condition, which comprises at once transferring the wound yarn packages at the spinning frame to containers which are sufiiciently airtight to prevent any but a negligible amount of evaporation of the solvent or swelling agent and are provided with orifices of diameter approximately equal to the diameter of the yarn, and feeding the yarn to the stretching machine through the said orifices while the packages remain in the containers.

8. A process for the manufacture of artificial yarns having a basis of cellulose acetate in which the yarns are produced by a spinning method which leaves in the yarns a small proportion of acetone, are wound up at the spinning frame, and are subsequently stretched while in a softened condition, which comprises at once transferring the wound yarn packages at the spinning frame to containers which are sufficiently airtight to prevent any but a negligible amount of evaporation of the acetone and are provided with orifices of diameter approximately equal to the diameter of the yarn, and feeding the yarn to the stretching machine through the said orifices while the packages remain in the containers.

DONALD FINLAYSON. FRANK BRENTNALL HILL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,019,376 Wilhelm Oct. 29, 1935 2,217,707 Samerdyke et a1. Oct. 15, 1940 

1. A PROCESS FOR THE MANUFACTURE OF ARTIFICIAL YARNS IN WHICH THE YARNS ARE PRODUCED BY A SPINNING METHOD WHICH LEAVES IN THE YARNS A SMALL PROPORTION OF A VOLATILE SOLVENT OR SWELLING AGENT FOR THE MATERIALS OF THE YARNS, ARE WOUND UP AT THE SPINNING FRAME, AND ARE SUBSEQUENTLY STRETCHED WHILE IN A SOFTENED CONDITION, WHICH COMPRISES HOLDING THE WOUND YARN PACKAGES UNDER CONDITIONS SUCH THAT EVAPORATION OF THE VOLATILE SOLVENT OR SWELLING AGENT IS SUBSTANTIALLY PREVENTED FROM THE TIME THE YARNS ARE WOUND UP AT THE SPINNING FRAME TO THE TIME THEY ENTER THE STRETCHING MACHINE. 